You can confirm you have a Revision 2 board by the presence of a hole at the west of the USB connector.

+

===Serial Port===

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Uses GIO pins 8 and 10 as TxD and RxD respectively which can then be accessed through serial port software such as Putty or the Java RXTX package. See [[RPi_Serial_Connection]] for details.

===Wireless: TP-Link TL-WN722N USB wireless adapter (Debian 6)===

===Wireless: TP-Link TL-WN722N USB wireless adapter (Debian 6)===

Line 136:

Line 233:

If you are now connected, well done! If not, check your editing and also have a look at the output of ''dmesg'' to see if you have any error messages. You can also view the system log for messages - for example: ''sudo cat /var/log/messages | more''

If you are now connected, well done! If not, check your editing and also have a look at the output of ''dmesg'' to see if you have any error messages. You can also view the system log for messages - for example: ''sudo cat /var/log/messages | more''

+

+

You are connected, you can ping and be pinged, hovewer to add network connectivity you may want to specify define default gateway:

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<pre>sudo route add default gw 192.168.1.254 wlan0</pre>

==Notes==

==Notes==

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iface wlan0 inet manual

iface wlan0 inet manual

</pre>

</pre>

−

in /etc/network/interfaces. Then sudo ifup wlan0 then sudo ifdown wlan0 then changing manual to dhcp. Works me, as described [http://unix.stackexchange.com/a/7717].

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in /etc/network/interfaces. Then sudo ifup wlan0 then sudo ifdown wlan0 then changing manual to dhcp. Works me, as described http://unix.stackexchange.com/a/7717.

Scan your network to see what wireless access points can be seen. You may need to do this to identify your network's SSID (name), but it also confirms that the wifi dongle is doing something. The first command just lists the SSIDs found, the second tells you probably more than you ever want to know:

sudo iwlist wlan0 scan | grep ESSID

or

sudo iwlist wlan0 scan

Create the wpa.conf file - eg: sudo vi /etc/wpa.conf:

Note: The ssid is case sensitive - if your WLAN's SSID is MYLAN, using "mylan" will not work - you won't connect!

If you are now connected, well done! If not, check your editing and also have a look at the output of dmesg to see if you have any error messages. You can also view the system log for messages - for example: sudo cat /var/log/messages | more

You are connected, you can ping and be pinged, hovewer to add network connectivity you may want to specify define default gateway:

sudo route add default gw 192.168.1.254 wlan0

Notes

USB interrupt/dma system debug messages

Firing up the TP-Link USB WLAN interface generates a lot of debug messages in the system log like this:

DEBUG:handle_hc_chhltd_intr_dma:: XactErr without NYET/NAK/ACK

Things may calm down a bit if the following file is created in /etc/modprobe.d (eg: sudo vi /etc/modprobe.d/smscnonturbo.conf) and then the RPi rebooted:

smscnonturbo.conf:

options smsc95xx turbo_mode=N

This fix may slow down wired LAN performance but help with wireless and reduce the frequency of the debug messages - YMMV. If you want to undo this fix, just delete the file (sudo rm /etc/modprobe.d/smscnonturbo.conf) and reboot.

Firmware requirements

If no wlanx device is shown, you might need to download firmware for your USB wifi device (or track down other compatible drivers if they are available). To confirm this, check the dmesg output when you plug in your adapter - typing dmesg at the command prompt may be sufficient - and look for information related to your adapter - the example dmesg output below shows what is seen in the event of the TP-Link firmware not being present - notice that the name of the required firmware file is given (htc_9271.fw), the driver name (ath9k_htc) and an error -22 message:

Armed with this information, try a web search for 'debian 6' and the name of the driver or driver file and/or head over to http://linuxwireless.org. Also check the links at the top of this page.

Power requirements

If you experience erratic network, keyboard, mouse or Raspberry Pi operation when using a USB wifi dongle, check that whatever is powering your RPi and/or USB hub can deliver sufficient current for everything that's connected together. The first setup tried with the TP-Link adapter had it, a keyboard, mouse and the RPi all connected to a Trust 7-port powered USB hub with a 5V 2A power supply, but in this configuration the mouse stopped working. In this case, the fix was to power the RPi from a separate 5V 1A phone power adapter.

wpasupplicant deamon failed to start

a) If you get this error when you attempt to

sudo ifup wlan0

Then there may be a syntax error in your

/etc/wpa.conf

For example, ensure that your SSID and Password have double quotes round them, and that the curly brackets are closed.